Resin transfer molding (RTM) has been used in forming fiber reinforced structures. When hollow structures are formed, inflatable bladders have been used as inner mold pieces.
A co-pending application to Freeman entitled "Perimeter Resin Feeding of Composite Structures", Ser. No. 06/833,304, filed 2-26-86, now U.S. Pat. No. 4,740,346 uses resin transfer molding (RTM). This application relates to the general subject matter of the present invention. Other patents relating to the subject matter of the invention include U.S. Pat. Nos. 4,017,572; 3,937,781; 4,473,520 and 4,269,890. The present invention differs from these patents and other prior art by a method involving injecting resin into fiber material and then using flexible means on both sides as the fiber is moved into the shape of the article being formed.
Different methods using RTM and inflatable bladder as an inner mold have generally involved multiple pieces to make the bladders nd involved steps in the process which limited the system to producing a limited number of parts within a given time span. The present invention involves an oversize bladder where stretching is minimized and the shape of the bladder is not critical.